破裂的管道故障原因弹性流马preduce工作在AWS上失败 [英] Broken Pipe Error causes streaming Elastic MapReduce job on AWS to fail
问题描述
一切正常，本地，当我做如下：
Everything works fine locally when I do as follows:
cat input | python mapper.py | sort | python reducer.py
然而，当我运行在AWS弹性麻preduce流马preduce作业时，作业未成功完成。通过 mapper.py 部分运行方式（我知道是因为写标准错误一路上这一点）。映射器是由一个破管道的错误，而我能够从任务企图的日志检索失败后中断：
However, when I run the streaming MapReduce job on AWS Elastic Mapreduce, the job does not complete successfully. The mapper.py runs part way through (I know this because of writing to stderr along the way). The mapper is interrupted by a "Broken Pipe" error, which I'm able to retrieve from the syslog of the task attempt after it fails:
java.io.IOException: Broken pipe
at java.io.FileOutputStream.writeBytes(Native Method)
at java.io.FileOutputStream.write(FileOutputStream.java:282)
at java.io.BufferedOutputStream.write(BufferedOutputStream.java:105)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65)
at java.io.BufferedOutputStream.write(BufferedOutputStream.java:109)
at java.io.DataOutputStream.write(DataOutputStream.java:90)
at org.apache.hadoop.streaming.io.TextInputWriter.writeUTF8(TextInputWriter.java:72)
at org.apache.hadoop.streaming.io.TextInputWriter.writeValue(TextInputWriter.java:51)
at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:109)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:441)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:377)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
at org.apache.hadoop.mapred.Child.main(Child.java:249)
2012-03-26 07:19:05,400 WARN org.apache.hadoop.streaming.PipeMapRed (main): java.io.IOException: Broken pipe
at java.io.FileOutputStream.writeBytes(Native Method)
at java.io.FileOutputStream.write(FileOutputStream.java:282)
at java.io.BufferedOutputStream.write(BufferedOutputStream.java:105)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:123)
at java.io.DataOutputStream.flush(DataOutputStream.java:106)
at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:579)
at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:124)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:441)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:377)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
at org.apache.hadoop.mapred.Child.main(Child.java:249)
2012-03-26 07:19:05,400 INFO org.apache.hadoop.streaming.PipeMapRed (main): mapRedFinished
2012-03-26 07:19:05,400 WARN org.apache.hadoop.streaming.PipeMapRed (main): java.io.IOException: Bad file descriptor
at java.io.FileOutputStream.writeBytes(Native Method)
at java.io.FileOutputStream.write(FileOutputStream.java:282)
at java.io.BufferedOutputStream.write(BufferedOutputStream.java:105)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:123)
at java.io.DataOutputStream.flush(DataOutputStream.java:106)
at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:579)
at org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:135)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:57)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:441)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:377)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
at org.apache.hadoop.mapred.Child.main(Child.java:249)
2012-03-26 07:19:05,400 INFO org.apache.hadoop.streaming.PipeMapRed (main): mapRedFinished
2012-03-26 07:19:05,405 INFO org.apache.hadoop.streaming.PipeMapRed (Thread-13): MRErrorThread done
2012-03-26 07:19:05,408 INFO org.apache.hadoop.mapred.TaskLogsTruncater (main): Initializing logs' truncater with mapRetainSize=-1 and reduceRetainSize=-1
2012-03-26 07:19:05,519 INFO org.apache.hadoop.io.nativeio.NativeIO (main): Initialized cache for UID to User mapping with a cache timeout of 14400 seconds.
2012-03-26 07:19:05,520 INFO org.apache.hadoop.io.nativeio.NativeIO (main): Got UserName hadoop for UID 106 from the native implementation
2012-03-26 07:19:05,522 WARN org.apache.hadoop.mapred.Child (main): Error running child
java.io.IOException: log:null
R/W/S=7018/3/0 in:NA [rec/s] out:NA [rec/s]
minRecWrittenToEnableSkip_=9223372036854775807 LOGNAME=null
HOST=null
USER=hadoop
HADOOP_USER=null
last Hadoop input: |null|
last tool output: |text/html 1|
Date: Mon Mar 26 07:19:05 UTC 2012
java.io.IOException: Broken pipe
at java.io.FileOutputStream.writeBytes(Native Method)
at java.io.FileOutputStream.write(FileOutputStream.java:282)
at java.io.BufferedOutputStream.write(BufferedOutputStream.java:105)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65)
at java.io.BufferedOutputStream.write(BufferedOutputStream.java:109)
at java.io.DataOutputStream.write(DataOutputStream.java:90)
at org.apache.hadoop.streaming.io.TextInputWriter.writeUTF8(TextInputWriter.java:72)
at org.apache.hadoop.streaming.io.TextInputWriter.writeValue(TextInputWriter.java:51)
at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:109)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:441)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:377)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
at org.apache.hadoop.mapred.Child.main(Child.java:249)
at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:125)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:441)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:377)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
at org.apache.hadoop.mapred.Child.main(Child.java:249)
2012-03-26 07:19:05,525 INFO org.apache.hadoop.mapred.Task (main): Runnning cleanup for the task
2012-03-26 07:19:05,526 INFO org.apache.hadoop.mapred.DirectFileOutputCommitter (main): Nothing to clean up on abort since there are no temporary files written
下面是 mapper.py 。请注意，我写信给标准错误提供自己与调试信息：
Here is mapper.py. Note that I write to stderr to provide myself with debugging info:
#!/usr/bin/env python
import sys
from warc import ARCFile
def main():
warc_file = ARCFile(fileobj=sys.stdin)
for web_page in warc_file:
print >> sys.stderr, '%s\t%s' % (web_page.header.content_type, 1) #For debugging
print '%s\t%s' % (web_page.header.content_type, 1)
print >> sys.stderr, 'done' #For debugging
if __name__ == "__main__":
main()
下面是我得到的标准错误的任务企图mapper.py运行时：
Here is what I get in the stderr for the task attempt when the mapper.py is run:
text/html 1
text/html 1
text/html 1
基本上，环通3次运行，然后突然停止，不蟒蛇抛出任何错误。 （注：它的应的可输出数千行）。即使是未捕获的异常应该出现在标准错误。
Basically, the loop runs through 3 times and then stops abruptly without python throwing any error. (Note: it should be outputting thousands of lines). Even an uncaught exception should appear in stderr.
由于马preduce运行完全没我的本地计算机上，我的猜测是，这是怎样的Hadoop是处理我从mapper.py打印输出的一个问题。但我无能，有什么问题可以。
Because the MapReduce runs completely fine on my local computer, my guess is that this is a problem with how Hadoop is dealing with the output I'm printing from mapper.py. But I'm clueless as to what the problem could be.
推荐答案
您流处理（你的Python脚本）被终止prematurely。这可能是做这想输入完成后（如跨preting的EOF）或吞咽异常。无论哪种方式，Hadoop是试图通过标准输入馈入到你的脚本，但由于该应用程序已终止（因此STDIN不再是一个有效的文件描述符），你得到一个BrokenPipe错误。我建议将标准错误的痕迹在你的脚本，看看有什么输入线引起问题。快乐编码，
Your streaming process (your Python script) is terminating prematurely. This may be do to it thinking input is complete (e.g. interpreting an EOF) or a swallowed exception. Either way, Hadoop is trying to feed into via STDIN to your script, but since the application has terminated (and thus STDIN is no longer a valid File Descriptor), you're getting a BrokenPipe error. I would suggest adding stderr traces in your script to see what line of input is causing the problem. Happy coding,
-Geoff
这篇关于破裂的管道故障原因弹性流马preduce工作在AWS上失败的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
